These days, it has been tried to grow III-V group compound semiconductor crystal on a Si substrate. Especially, the growth of GaAs which is a typical one of III-V group compound semiconductor crystals has been most actively studied in the research and development. In a conventional process for the growth of GaAs on a Si substrate, a single crystal GaAs layer is grown on an amorphous GaAs layer which is grown on a Si substrate at a low temperature to function as a buffer layer because it is difficult to grow a GaAs layer with a good quality directly on the Si substrate. The conventional process has been proposed to be "a two temperature growing process" as described on pages L843 to L845 of "Japanese Journal of Applied Physics, Vol. 23, No. 11, Nov. 1984".
In a general process for growing GaAs layer such as molecular beam epitaxy (MBE), metalorganic chemical vapor deposition (MOCVD) and so on, however, a GaAs layer of a good crystal property is not grown because a continuous film of the GaAs layer is not obtained, but island like film thereof is resulted in a case where a single crystal GaAs layer is tried to be grown directly on a Si substrate.
Otherwise, a continuous film of a amorphous GaAs layer is obtained when a growing temperature is lowered therein. Then, when the amorphous GaAs layer is subject to a heat treatment, it is crystallized to be a single crystal as the aforementioned buffer layer. Even in a process for the growth of InP layer, InGaP layer etc., a similar amorphous buffer layer is utilized in the same manner as described above.
In the conventional MBE process in which Ga metal is utilized or the conventional MOCVD process in which trimethyl-Gallium(TMG) or triethyl-Gallium (TEG) is utilized in the two temperature growing process, however, there is a disadvantage that a predetermined selective growth property is not obtained because a polycrystal is grown on a SiO.sub.2 mask provided on a Si substrate.
Accordingly, it is an object of the invention to provide a process for the growth of III-V group compound semiconductor crystal on a Si substrate in which a III-V group compound layer of a good crystal property is grown on a Si substrate.
It is a further object of the invention to provide a process for the growth of III-V compound semiconductor crystal on a Si substrate in which the selective growth of a III-V group compound layer is performed on a Si substrate.
According to the invention, a process for the growth of III-V group compound semiconductor crystal on a Si substrate comprises,
placing a Si substrate on a mount positioned in a growing chamber,
heating said Si substrate at a predetermined temperature,
supplying first gas seed including one selected from In and Ga of III group elements, and second gas seed including one of V group elements alternately into said growing chamber,
and growing III-V group compound semiconductor crystal on said Si substrate,
wherein said one selected from In and Ga is a chloride thereof.